Video adapter circuit for detection of analog video scanning formats

  • US 5,953,074 A
  • Filed: 10/10/1997
  • Issued: 09/14/1999
  • Est. Priority Date: 11/18/1996
  • Status: Expired due to Term
First Claim
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1. A method of detecting a format of an analog video signal having a horizontal sync signal and a vertical sync signal the method comprising steps of:

  • a. counting a first number of pulses of a clock signal occurring when the horizontal sync signal is a low voltage and counting a second number of pulses of the clock signal occurring when the horizontal sync signal is a high voltage;

    b. determining whether the first number or the second number is within a first predetermined range of values;

    c. counting a third number of pulses of the horizontal sync signal occurring when the vertical sync signal is a low voltage and counting a fourth number of pulses of the horizontal sync signal occurring when the vertical sync signal is a high voltage;

    d. determining whether the third number or the fourth number is within a second predetermined range of values; and

    e. determining whether the first number or the second number is equivalent to one of a plurality of numbers of pixels in a horizontal line associated with a video format.

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